I've been looking into turbo/high powered setups, and started thinking about the effects on the car. Despite that, don't think about my set up in relation to all this, that's just what's inspired all these questions... And FWIW this is (at the moment anyhow) strictly straight-line scenario.
Anywho, big power in the engine results in big force spinning the wheels, but in the process of that force is being shifted from piston to crank to fly to clutch to gears to driveshafts to wheels to rubber. "A chain is only as strong as it's weakest link", so!;
1. Forged internals are easy to come across. rods, valves, valve springs, etc. These have been covered to death on every corner of the internet... What about crankshafts? Is there a certain point these need to be looked at? I'd imagine most street cars are running stock/modified stock cranks at best? Looking at the layout of a crankshaft, I'd imagine these are a particularly hard wearing item. While we're still in the engine, I'm guessing fresh bearings are more than enough for street applications. Regarding race cars etc, what type of bearings do they use? I'd guess it's a bearing that's applied the exact same way as street cars, just made of different compounds? A carbon-moly or something?
Noss was spot on, KA crank is forged. If you do not plan on increasing your maximum rpms over 6500, if you have it prepared correctly, i.e. balanced with the crank pulley, flywheel and clutch cover, chamfer and radius the oil galleries etc, it will serve you well. Only if you anticipate increasing your maximum rpms over 8000, do you need to consider a fully counterweighted crank.
the only guy I ever heard of lunching a prepared KA crank was due to regular pulls to 8000rpm, that was on a significantly worked KA24DE.
Standard bearings from Nissan are the go, the key is to ensure that clearances are exactly spot on.
2. Flywheels and clutches are easy enough to come across as well. Lightweight strengthened flywheels are available for every car. Point in case you can buy one for the pintara. and it's also been covered quite succinctly on ANTRX. Regarding clutches, specifically button clutches (ignoring multi-disc/different compounds, since these have been covered to death again), 4-puck = race, 6 puck = streetable race. I get that it refers to the amount of notches on the clutch disc (or correct me if I've been silly enough to take misinformation from the internet as absolute fact), but I don't understand why a 6 puck grabs 'softer' than a 4 puck?
Can't really comment on this one, but yes, I would go for a lighter flywheel. Regarding clutches...I only have experience with full faced ones in my U12's. I expect that my Exedy clutch in my black car will crap out despite only having 10,000-ish kms on it when I finally get this god damn turbo in later this year.
3. That brings us to the transmission. Certain boxes are stronger than others (hurr hurr... "box" - you know someone was going to do it, and now that it's out of the way.. ) etc. But when the bigger figures come in, what is it that determines the strength of a complete gearbox? I'd imagine it's a function of the thickness of the carbon coating on the gears (or whatever they used at the time depending on age), how well things still align (i guess this would fall under general 'age' of the box), and the type of material the core of the gears are made of? Not to mention oil coatings obviously. If we introduce human error into this it gets a bit messy, I'd like not to consider it too heavily for the time being... But regarding reinforcement, is it as simple as just a carbon coating on the gears, allow it to "set" into the metal so that it blends properly, and we're done? I'd imagine a good carbon coating would also anneal any cracks/defects on the outer surface. Excuse my first year metallergical take on this, it's all I've got to work with atm
Again, no hands on experience here, but I have heard from reliable sources that the RS5F50 box (either A, non lsd or V, lsd variant) is only likely to take a dump if you are trying to do rather high rpm launches on full slicks, in which case you would probably pop one or both driveshafts first.
As a minimum, if I had a gearset apart, I'd send it off for cryotreating. Reputedly it helps.
4. Diffs I have no idea about. They're a magical box that makes sure the driveshafts spin at a power distribution equal to something close to the amount of grip they've got. I vaguely understand how the viscous diff works (a thick 'oil' i guess? is inside with the two driveshafts such that if one starts spinning faster the oil starts spinning with a rotational frequency equal to the quicker shaft thus spinning the lagging shaft a bit faster), but that's about it. Since I have no idea how this works I couldn't rightfully ask how to improve it! I'd assume a mechanical diff would be more desirable since the viscous liquid would have a considerable 'spin up' time in terms of one driveshaft 'seeing' the other spinning faster.
5. So we're out of the transmission and diff, heading down the driveshafts. I can appreciate there'd be a fair amount of torsion being applied at one end of the driveshaft compared to the other (assume the clutch has just been dumped or something similar), leading to stress in the material. Even on regular driving there'd obviously be a slight "lag" in the rotation of the metal at the wheel as opposed to at the diff. Or am i over exagerating? I could appreciate that i'd be wrong as far as daily driving is concerned, but thinking of the 600rwkw or so that the V8s put out, that's some serious strain on the material. What do they make those things out of?
Quaife do a mechanical clutch type LSD for the Maxima using the same RS5F50 manual gearbox, but it is about $2k.
Regarding driveshafts, AFAIK the only way you should be able to pop one is on full slicks, and over 300 fwkw. Even then, it will be the CV joint or the splines that will fail.
6. Rims and rubber. 'nuff said. Get better rubber, it wears faster (generally).
215's with standard springs will rub in a U12. They do not with King Low's.
Wheel width of 7" is about the limit before you have to started thinking about guard mods and offsets in the range of 0 up to +20.
7. Chassis. Didn't want to touch this since this opens up a whole can of worms my head isn't ready for, but it does need to be mentioned i suppose. The saying "A chain is only as strong as it's weakest link" rings true here. Big power = big force. If you don't reinforce the chassis, GG.
Repair any rust in structural members. From memory a former member damaged his cross member mounts as a result of some unnoticed corrosion and increased torque loading from the motor (turbo KA)
And you're right, chassis mods should only be on the table if the car is coming apart and you have time to spend on spot welding / cage fabrication etc.
As for bolt on bracing, the LCA brace does help, strut braces I cannot comment on. the only stb i built is on another antrx member's U12 who doesn't seem to frequent here much anymore. Never got any feedback from him unfortunately.
Regarding the chassis rail foam filling, I never ended up doing it; from what research I did, it was only heresay on the final result.
I may look into it again for my daily driver, but for my black U12, it's staying foam free.
Btw, with that car....it's nothing special at all. I have never posted pics of it because I knew that certain members of Victoria's Highway Patrol used to do the rounds of car forums and targeted specific owners and vehicles....case in point our own Noss.
We were out one weeknight at a meet point about to head off to "observe" some spirited driving down on Princess Hwy near Westall rd....next thing as we were about to take off, HWP rock up and have a chat to Noss about his R32 tails....said they'd been looking for him for a while.
Anyway...I haven't driven it for over 8 months since I've had my daily TRX, which used to be Budge's.
As it stands, it has:
Cobra Monaco fixed back seats on custom adaptors fabricated by yours truly
Just Jap quick release steering hub
Techedge 2B0 wideband
Moates Ostrich 2.0 for realtime ECU tuning
Solid lifters, Wade cams 262/264 cam, self ported heads (groan....when that head comes off this engine, it's getting sliced up in my bandsaw for r&d)
Genie extractors, with standard cat and a sad ass 2.0" mandrel bent exhaust, good for 7psi of fail (back pressure). Extractors will probably end up on my daily, exhaust is going in the bin to be replaced by a full 3" system.
King low's all round (need replacing), Koni reds in the red (to be revalved), some form of pedders shit in the front (to be replaced by custom valved bilsteins and coilover sleeves)
urethane bushes front and rear, to be replaced with delrin first, then heim joints later
17x7 rims with 215/40/17 Yokohama's, being replaced with Wedsports TC-05's in 15x6.5 and 195/50/15 Federal RSR's as my initial track wheels. These TC-05's a very, very light
R32 GTS-T 4 piston front calipers with 30mm thick 276mm slotted rotors
Whiteline 24mm rear sway bar with custom mounts
Battey relocated to the boot
No sound deadening
No AC
No stereo
Weighs about 1190kg with a full tank and the 17's, to get much lighter
And a paint job that really needs to be resprayed.
At the moment I've got the entire front off it so I can easily fabricate the mounts for the Spal 12" pusher fan that is replacing the standard thermos, so I can get the Garrett GT3040 and 44mm Tial wastegate in before xmas this year.
Then off to grenade this engine at Phillip Island or Winton. Woot.